Detergent tablet and process of preparing same



United States Patent 3,247,122 DETERGENT TABLET AND PROCESS OF PREPARINGSAME Bernard Richard Schaa-fsma, Midland Park, and Albert LyleSchulerud, Nutley, N.J., assignors to Colgate- Palmolive Company, NewYork, N.Y., a corporation of Delaware No Drawing. Filed July 30, 1962,Ser. No. 213,116 9 Claims. (Cl. 252-135) The present invention relatesto an improved process for making detergent tablets. More particularlythe invented process is of a method of producing such tablets whichfacilitates their commercial manufacture, even when production must betemporarily interrupted for such causes as mechanical breakdowns,cleaning of equipment and absence of the operator of the processingequipment. The invention also includes detergent tablets of a newcomposition.

In the production of lightly compacted detergent tablets, made fromsmall detergent particles, it has been found that certain formulascomprising non-cationic synthetic organic detergent, water solublesilicate, water soluble polyphosphate and Water result in a quicklydisintegrating tablet, completely soluble in water, which is of a lowbulk density and is capable of withstanding shipping shockswithoutfracture. In the production of such a tablet, moisture is addedto detergent composition particles before they are pressed to tabletform. By following the novel procedures of the present invention, theease of manufacturing such tablets can be dramatically increased. Thisis so, due to the addition-of a small proportion of water solublesulfate to the detergent composition, which makes detergent particleswhich can be moistened and which show little tendency to agglomerateobjectionably moistening, despite remaining quiescent for substantialperiods of time. Detergent tablets can be produced without the presenceof the water soluble sulfate but the ease of processing obtainable bythe present method represents a distinct improvement which was notexpected from the prior art or practice.

In accordance with the present invention a process for manufacturing adetergent tablet comprises producing a particulate detergent compositioncomprising about 2 to 20% of a non-cationic synthetic organic detergent,about 25 to 40% of a water soluble polyphosphate, about 20 to 50% of awater soluble metal silicate, about 3.5 to 10% of water soluble sulfateand up to about water, moving and circulating a mass of said particulatedetergent, adding 2 to 30% water to the moving and circulatingparticulate detergent to raise the moisture content thereof to 17 to 30%and lightly compacting the resulting particles to form retaining tabletswhich are readily disintegrable in wash water, soluble therein andresistant to breakage when subjected to shipping shocks.

The non-cationic synthetic organic detergent is usually a nonionicdetergent, preferably one comprising both hydrophilic and hydrophobicportions in the molecule of which at least the hydrophilic portionincludes a plurality of lower joined alkylene oxide groups. A preferreddetergent of this type is an alkyl phenol having a poly lower alkoxyalkanol joined to the phenolic oxygen. Nonyl phenoxy polyoxyethyleneethanol, comprising about 9 to 10 ethoxy groups, has been found to be anexcellent nonionic detergent of the present invention. Usually, insteadof nonyl, the alkyl group may be of 6 to 14 carbon atoms and the alkoxychain may be of 4 to 12 alkoxy units, each unit comprising from 2 to 4carbon atoms. Although the above-mentioned phenolic derivatives are of aspecial importance in this invention, mixtures of nonionic detergentsmay also be employed. Thus, other nonionics, including the blockcopolymers of ethylene oxide and 'propylene Patented Apr. 19, 1966 oxide(Pluronics), reaction products of higher fatty alcohols and loweralkylene oxide (Emulphogene), polyoxyethylated higher fatty acids(Emulphor), polyethoxy and poly lower alkoxy esters and ethers of polyalcohols, especially of sorbitol and mannitol (Span, Tween) may be usedwith the alkyl phenoxy polyoxyalkylene alkanol and in replacementthereof, where desired. Whether a single type of nonionic detergent or amixture thereof is used, the proportion should be within the range of 2to 20%, preferably 5 to 15 or 6 to 14% of the detergent briquette. Allpercentages of constituents in this specification and in the appendedclaims are on a tablet weight basis.

In addition to the nonionic detergent one may have present in thedetergent tablet, as replacement of some of the nonionic detergent, ananionic detergent, usually added primarily to produce additional foam,when desired and to contribute its cleaning power to the composition. Insome cases it may be found desirable to replace nonionic detergent witha suitable anionic material. A preferred anionic detergent is sodiumalkyl benzene sulfonate, especially sodium tridecyl benzene sulfonate.This material is a mixture of detergents produced by alkylating benzenewith a blend of propylene tetramer and pentamer. The alkyl groups arehighly branched but other alkyls of relatively straight chainconfiguration are also useful in these compounds, providing that theyare of 12 to 18 carbon atoms. The anionic detergents are generallyemployed as their water soluble sodium salts but other Water solublemetallic salts, such as the alkali metal salts, e.g., potassium salts,may be used too, usually in partial replacement of some of the sodiumsalt. Instead of alkyl aryl sulfonates, other anionic organic detergentsof the sulfated or sulfonated type are useful. Of these, one may mentionsodium lauryl sulfate, sodium coconut oil fatty acids monoglyceridesulfate and sodium salts of a higher fatty acid amide of N-methyltaurine. It will be seen that these compounds contain a fatty alkyl oracyl group of 10 to 18 carbon atoms, as the lipophilic portion of themolecule and are utilized as their water soluble salts, preferablyalkali metal salts. The proportion of anionic detergent which may beused to make a detergent tablet is complementary to that of the nonionicdetergent. In other words, the sum of both types of detergent materialpresent should not be in excess of about 20% and not less than about 2%of the detergent briquette.

The water soluble metal silicate is a constituent of the presentbriquette which has the unusual effect of aiding the production of abriquette which-is form-retaining and resistant to breakage, althoughpressed at a low pressure,

and still disintegrates rapidly in aqueous media and dissolvescompletely in a short time. The silicates allow making of tablets of lowbulk density and do not require coating of the tablets. Of the silicatesthat have been found useful, those which are alkali metal salts,especially sodium silicates, and which are of a ratio of metal oxide tosilica, by weight, of about 0.3 to 0.6 are most often used. A highlypreferred silicate is sodium metasilicate having a Na O:SiO ratio of1:235. However, other silicates of the general type described may alsobe included in the present briquettes, either together with or inreplacement of this particular silicate, to obtain similar effects.

The water soluble polyphosphate is a metal salt, usually an alkali metalsalt and preferably the sodium salt of a polyphosphoric acid. Among suchsalts, the most preferable are pentasodium tripolyphosphate andtetrasodium pyrophosphate. Other polyphosphates of satisfactory builderaction, Which also enable one to produce improved briquettes, accordingto the present invention, may be employed in mixture with the describedsodium polyphosphates or in replacement thereof. Either the sodium orpotassium salts of these materials are used, depending upon theparticular properties of the final product desired. The water solublesulfate is the material which, when presentin the detergent particles tobe moistened, together with the other detergents and builders mentioned,has the unexpectedly beneficial effect of improving processingproperties markedly. The sulfate is usually an inorganic compound,generally a metal salt. Most preferred of these is sodium sulfate butother alkali metal sulfates, e.g., potassium sulfate, may be employedproviding that they have the same general effect with the composition towhich they are added. In addition to the four constituents described,water must be present in the final tablets. Also, adjuvants which areuseful to give the detergent briquette special desirable properties maybe ineluded. Among such substances are additional builders, foamenhancers or suppressors, coloring agents, per fumes, bleaches,solvents, fluorescent dyes, anti-redeposition agents and so forth. Thetotal proportion of adjuvants employed should be a minor one, to avoidany interference with the desirable physical properties of the detergentbriquette.

The proportions of non-cationic detergent, silicate, polyphosphate,sulfate and water should be regulated in accordance with the followingteachings so as to obtain a product which can be economically andefficiently manufactured by the method herein described and which willstill be of satisfactory strength and solubility properties. Theproportion of the synthetic organic detergent should be held within therange of 2 to 20% and is preferably 6 to 14%, most preferably about Ithas been found that, in conjunction with the silicate and phosphate,such a percentage of organic detergent will give excellent cleaningresults and will not interfere with the production of a strong, yetquickly dissolving tablet. Lesser proportions than the minimum of thisdetergent will not have a satisfactory cleaning effect and higherproportions will often interfere with the desired tablet properties. Thewater soluble phosphate present should be 25 to 40% of the briquette,preferably about 30%. Such percen tages of these materials contributeexcellent building and detergent properties to the product andcomplement the silicate to allow the production of a quick dissolvingtablet of adequate strength and abrasion resistance. Also, suchproportions of the polyphosphate may be completely hydrated by some ofthe water present, leaving additional moisture to aid in making thesilicate more readily soluble in the wash water.

The water oluble silicate comprises to 50% of the briquette andit hasbeen found that such a proportion of silicate is desired to obtain aproduct which will dissolve rapidly and yet which will be of excellentresistance to breakage during normal shipping. A preferred proportion ofsilicate is 20 to 40% and about 30% is considered best. The silicateconstituent of these products, when employed in these proportions,exhibits a dramatic effect in modifying the tablet properties, makingthe tablet lighter, yet stronger, helping the particles to be joinedtogether more tightly, so as to diminish a tendency to break under roughhandling, yet promoting very rapid solubility. These beneficial resultsmay be obtained without surface coating the detergent briquettes, whichis unexpected. The proportion of Water present in these briquettes isimportant to obtain a satisfactory product having the propertiesdiscussed previously. The water substantially or completely hydrates thepolyphosphate and also greatly improves the solubility of the silicate,so that virtually no insoluble grains are found in wash water into whichbriquettes have been placed. Seventeen to 30% of water in the inventedbriquettes will accomplish these results and it is preferred to employ19 to of water in most of the invented compositions, most preferably 21to 23% whereby substantial hydration, e.g., 75% hydration or more, ofthe polyphosphate takes place. Moisture added to the particulate 4detergent is 2 to 30%, preferably 7 to 17%. It has been found thatwithin the ranges mentioned more water can be included in the briquetteswhen silicates of lower ratios of Na O:SiO within the 0.3 to 0.6 range,are used.

The proportion of sodium sulfate in the detergent tablets to obtainimproved processing properties is from 3.5 to 10%. This may be obtainedby producing a particulate detergent having about 4 to 12% sodiumsulfate therein, allowance being made for the decrease in the proportionof the sodium sulfate caused by addition of moisture. With respect tothe other constituents of the invented tablets, the same percentageranges were given for both the final tablet and the particulatedetergent composition from which it is made, to avoid unnecessaryinclusion of additional ranges of constituents in the particulatedetergent. It is understood that the ranges given primarily describe thefinal product and the crutcher mix composition and particulate detergentcomposition will usually be chosen accordingly.

When 3.5 to 10%, preferably about 7%, of sodium sulfate is included inthe detergent tablet, it is found that moving and circulating of themass of particulate detergent to which water has been added may besuspended for as long as an hour Without any detrimental agglomerationof the product into lumps or units of undesirable size and hardness.Thus, should it be required to halt mixing or should some material haveto be held before pressing, this can be done without the necessity forscapping of treated detergent. Also, production can be made moreefficient because a holdup reservoir or bin may be installed before thepresses and it is not essential that the pressing rate be exactly equalto the rate of feed from the spray tower to the apparatus in which theparticles are moistened.

To manufacture the present detergent tablets, a particulate detergent isproduced in which the organic detergent, sulfate, silicate and.polyphosphate are present. It is highly preferred that such detergentcomposition constituents be homogeneously distributed throughout thearticles and spray dried detergent beads have been found to be anexcellent starting material for making these briquettes. In the spraydrying operation, one makes a solution or slurry of the detergentmaterials in an aqueous medium, usually adding to this crutcher mlxuseful adjuvant substances which are not adversely affected by spraydrying. Normally, the crutcher mix will be of a solids content withinthe range of about 40 to 60%. This aqueous dispersion or solution isthen pumped through spray nozzles and is dried in a path of heateddrying gas, through which it usually falls to a collector. The particlesproduced may be cooled, screened and classified to remove objectionablylarge or small material. The product resulting may be somewhat irregularin shape but is usually considered to be composed of bodies which arehollow and of approximately spherical shape. Those of particle size suchthat over pass through an 8 mesh sieve and do not pass a mesh sieve, aUS. Standard Sieve Series, are excellent beads to be converted intobriquettes or tablets. During the drying operation most of the Waterpresent in the crutcher mix is removed but there may be left in theparticles up to about 15% of moisture, and usually at least 1% ispresent.

The homogeneous detergent composition particles may be produced by othermethods than spray drying. For example, spray cooling, agglomeration,even crushing, followed by screening and classification, may be employedto produce the desired particles. Also, a portion of the product may bespray dried and to this may be separately added organic detergent,silicate and phosphate. However, it is considered important to have asubstantial proportion of the silicate present, at least about 75%thereof, present with the phosphate and organic detergent anddistributed throughout each of the particles, as in a spray driedcomposition.

The particles of detergent composition, high in silicate content, asdescribed above, are placed in continuous motion as in la tumbling drum,and while moving, moisture is sprayed onto the particle surfaces in finedroplet form and in amount to produce a final product having a moisturecontent of 17 to 30%, preferably 19 to The continuously moving andcirculating particles may adhere lightly to a number of other particles,in the course of spraying and circulating them. Before moistening, thedetergent beads are of an apparent density of about 0.2 to 0.6 gram percubic centimeter. After moistening, this density may be alteredsomewhat, usually being decreased, e.g., by as much as This result isattributable to the moistening of the relatively large proportions ofsilicate together with polyphosphate and the resulting swelling ofmaterials and increase in average particle size.

Adequate and uniform moistening of the detergent beads or granules highin silicate content maintain the silicate in a readily soluble conditionso that no undissolved silicate deposits on clothing being Washed. Thisis of importance to the detergent chemist because silicates tend tobecome more insoluble when heated to drive off the moisture accompanyingthem, as is done in spray drying. Also, the polyphosp'hatespreferentially attract moisture, thereby often tending to reduce thesilicate to a less soluble state. Even when placed in an excess ofwater, as in the washing machine, such silicates may not dissolvecompletely during the wash cycle, leading to objectionable particlesleft on the articles being laundered. On the present detergentbriquettes however, due to the relatively high concentration of silicatesolution produced when the composition high in silicate content ismoistened, any silicate of lower solubility is soon made more soluble.This more soluble form or condition persists for long periods of timeafter moistening, and the briquette produced therefrom is stillcompletely soluble, months after it is made. A most even distribution ofmoisture in the detergent and an absence of excessive agglomeration arenoted when the material beingmoistened is kept in continuous motion andthe moisture is applied in fine droplet form. Mixing, moistening, andagglomeration to a desired extent may be followed by screening thepressed detergent to desired particle size range. It has been foundpreferable to have the particles between 4 and 40 mesh, US. StandardSieve Series, but other size ranges may be utilized. When moisture isadded to particles initially of very low moisture content, it has beenusually found more difiicult to add large proportions of moisture,within the ranges mentioned, than to add lesser amounts thereof. Also,it is usually desirable to add more than the minimal proportion ofmoisture when the particles are initially comparatively dry. Theoperator of the mixing equipment will normally adjust his mixingtechniques, speeds, and times to produce the most desirable moisteningof the detergent particles. Also, two-step addition of moisture may befound desirable, wherein an initial amount of moisture is added, mixedfor a sufficient length of time, perhaps 5 minutes to as long asone-half hour, and then a second addition of moisture is made. By thistechnique, one can add larger percentages of water to the detergentparticles and still obtain excellent pressable material. As mentioned,mixing speeds may be adjusted, as may mixing times. However, mixingspeeds of 100 to 250 lineal feet per minute, at the exterior of arotating drum, equipped with internal bafiies have been found useful.Mixing times of as little as one minute can give acceptably moisteneddetergent particles.

Due to the presence of the sulfate in this composition, the moistenedproduct is not sensitive to undesired aggregation into lumps or concretemasses. Thus, the moistened detergent may be held as long as an hour ormore in some instances and will still be free flowing, suitable fortransport to the press. The reason for the unexpected effect of therather specific proportions of sulfate is not known, although it istheorized that the sulfate enters into and regulates the speed ofhydration of the other salts present, thereby changing the type ofaggregate produced.

After moisture has been added to the silicatecontaining detergentparticles, they are pressed at a low pressure into a desired briquetteform. The pressure employed may be any suitable low pressure, it havingbeen found that pressures from 3 to 25 pounds per square inch may beused advantageously in pressing a table, which is most often from aboutA to 1 inch thick. Pressures over pounds per square inch should beavoided. Pressing is preferably effected between opposed dies havingTeflon or chrome plated surfaces and cavities. After pressing, it isunnecessary to submit the product made to any special treatment or agingperiod before it may be shipped although as ignificant increase instrength is observed within about an hour after pressing. The detergentbriquettes prepared are of suflicient strength to withstand shippingwithout breaking or being severely abraded and they may be packed in anyusual way. It has been noted that the briquettes made often have highlydesirable low densities, making a tablet whose larger volume is easierfor the user to employ and which facilitates subdivision into smallunits, where accurate control of the detergent concentration employed isconsidered important. It is considered unpredictable that the detergentpowder and tablet bulk densities should be of such desired low densitiesin the claimed formulas, from 0.2 to 0.6 gram per cubic centimeter,since previous observation indicated that sulfates tended to increasesuch densities. Surprisingly, too, the lighter briquettes are evenstronger than comparable heavier materials made with less silicate. Theyare made by a more efficient process and can be produced by tabletingand briquetting equipment of conventional design. Due to the eliminationof a coating operation, heretofore considered to be necessary and stillconsidered important for many other detergent tablet formulations,production rates and efficiency can be increased. Furthermore, all thisis accomplished without the necessity for inclusion of comparativelyexpensive conditioning or adjuvant materials in the detergents.

Although it is'unnecessary to coat the detergent to make a satisfactoryproduct of this invention, moisture may be sprayed onto the surfaces ofthe finished briquettes, if so desired. Also, it may sometimes beconsidered desirable to deposit a thin film of organic polymer, such assodium carboxy methyl cellulose or polyvinyl alcohol on the productsmade, to further harden them and make them suitable for withstandingextremely severe handling. Gther variations of the described processwill be apparent to one of skill in the art but the described inventionmakes a useful product and modification of the production method is notnecessary, although it may sometimes be desirable. In some cases it ispossible that the moistening solution may include adjuvant materials notstable to heat, e.g., emulsified perfumes. Some sodium silicate may beadded with that solution. Products produced may subsequently beperfumed, colored, wrapped and packed for shipment. It is preferred topack them in moisture tight wrappers, e.g., sleeves of polyethylenefilm, but they are still resistant to breakage and are usefully soluble,even when stored for months at atmospheric conditions.

Products made according to this invention have been subjected to severetesting and usually, after aging, a briquette can stand at least fiveshocks equivalent to a free fall of four feet onto a hard surface beforeit starts to break apart. Also, when packed in polyethylene sleeves, thebriquettes do not become abraded objectionably, despite repeated shakingin a package, which simulates a type of rough handling to which they maybe subjected in shipping. Still, despite their great strength,

the tablets dissolve quickly and completely, usually disintegratingcompletely within 45 seconds and most often in 10 to 30 seconds. Thefollowing examples are included to illustrate embodiments of theinvented process and products. They are not to be considered as limitingthe invention. All proportions are by weight, unless otherwiseindicated.

An equeous crutcher mix was made of all the above materials except thepigment and the approximately 55% solids mix was sprayed at a pressureof about 300 pounds per square inch and at a temperature of 135 F. intoheated drying gas at an initial temperature of about 600 F. Theparticles obtained, of about 8 to 100 mesh, were of a moisture contentof about 10%. They were sprayed with a fine spray of water while beingtumbled for to minutes in a slightly tilted drum rotating at aperipheral linear speed of about 100 to 250 feet per minute. Sprayedproduct was continuously removed at a moisture content of 21% and wasscreened to 4 to 40 mesh (through 4, on 40 mesh), after which it washeld for periods up to an hour and pressed. This product may also beheld several hours and is still pressable. It does not lumpobjectionably on storage.

The powder before pressing is of a bulk density of about 0.25 gram percubic centimeter, the spray dried powder being approximately 0.3 gramper cubic centimeter. It is pressed to a chamfered flat cylindericaltablet of 2% inches diameter by 0.815 inch thickness, weighing 1.3ounce, being of a bulk density of about 0.5 gram per cubic centimeter.Pressing was at a pressure of about 5 to 25 pounds per square inch.

The tablet made was an excellent laundry detergent. It was quicklydisintegrable in wash water in a typical washing machine. When tested bydropping 2 feet onto an end, immediately after manufacture it did notbreak up. After aging several hours or overnight the tablet strengtheven increases, as it does when 2 to.5% moisture is sprayed onto thetablet surface followed by drying off of such added moisture.

Example II Ingredient:

Higher alkyl phenol polyethylene ethanol (alkyl of nine carbon atoms andpolyoxyethylene ethanol chain averaging 9.5 ethyl- Parts ene oxidegroups) 10.4 Sodium tripolyphosphate 32.3 Sodium silicate (Na O:SiO=1:2.35) 31.6 Sodium sulfate 3.5 Water 21.0 Adjuvants 1.2

8 placed in the wash water in a washing machine. Its abrasion resistancewas very high, due in part to the post treatment with water.

This formula resulted in moistened beads which did not lump, and weremobile enough to be moved by and to processing equipment, even after asmuch as /2 hour of quiescent storage. In this respect it was farsuperior to a similar formula less the sulfate constituent.

' Example III Ingredient:

Parts Ethoxylated nonyl phenol (9 to 10 ethylene oxides per mole) 10.0Sodium tripolyphosphate (including phosphate products of spray drying)40.0 Sodium silicate (Na O:SiO ratio of 112.35) 20.0 Sodium sulfate 8.0Adjuvants (pigment, fluorescent dyes, perfume, inert materials) 1.0Water 21.0

The above formula is for a detergent briquette processable by the methodof Example II. The product obtained is acceptable as a laundry detergenttablet, although the detergent particles produced are of higher bulkdensity than those made with more silicate. In part, this effect may beattributable to the spray properties of the crutcher mix and subsequentdifferences in moistening effects. The detergent particles processedwell and did not lump objectionably or exhibit a laziness afterstanding.

Example IV A tablet of formula like that of Example II was made, exceptfor replacement of the 3.5 parts sodium sulfate with 10.0 parts and thechanging of the moisture content to 23%. The product produced wascomparable to that of Example II and processed readily, exhibiting nolaziness.

The invention has been described with reference to several examplesthereof. It is not to be limited thereto and its scope is determined bythe claims and processes and products equivalent to those claimed.

What is claimed is:

1. A process for manufacturing a detergent tablet which comprisesproducing a particulate detergent composition comprising 2 to 20% of awater-soluble synphilic and hydrophobic portions in the molecule inwhich at least the hydrophilic portion includes a plurality of lowerjoined alkylene oxide groups or mixtures thereof, 25 to 40% of awater-soluble alkali metal polyphosphate, 20 to 50% of a water-solublealkali metal silicate, 4 to 12% of a water-soluble alkali metal sulfateand up to about 15% water, moving and circulating a mass of saidparticulate detergent, adding 2 to 30% water to the moving andcirculating particulate detergent to raise the moisture content thereofto 17 to 30% whereby the moisture is substantially uniformly distributedthroughout the mass of said particles. and lightly compacting theresulting particles at a pressure of 3-100 p.s.i. into form retainingtablets which are readily disintegrable in wash water, soluble thereinand resistant to breakage when subjected to shipping shocks.

2. A process for manufacturing a detergent tablet which comprises spraydrying a particulate detergent composition comprising 2 to 20% of awater-soluble nonionic detergent containing both hydrophilic andhydrophobic portions in the molecule in which at least the hydrophilicportion include-s a plurality of lower joined alkylene oxide groups ormixtures thereof, 25 to 40% of a water-soluble alkali metalpolyphosphate selected from the group consisting of pyroph'osphates andtripolyphosphates, 20 to 50% of a water-soluble alkali metal silicatehaving a metal oxide to silica ratio between 0.3 and 0.6, 4 to 12% ofwater-soluble alkali metal sulfate and up to water, moving andcirculating a mass of said particulate detergent, adding 2' to 30% waterto the moving and circulating particulate detergent to raise themoisture content thereof to 17 to 30% whereby the moisture issubstantially uniformly distributed throughout the mass of saidparticles and lightly compacting the resulting particles at a pressureof 3-100 p.s.i. into form retaining tablets which are readilydisintegrable in water, soluble therein and resistant to breakage whensubjected to shipping shocks.

3. A process for manufacturing a detergent tablet which comprises spraydrying a particulate detergent composition comprising 6 to 14% of anonionic synthetic organic detergent which is a higher alkyl phenol polylower alkoxy alkanol, 25 to 40% of a water-soluble alkali metaltripolyphosphate, to 40% of a watersoluble alkali metal silicate ofmetal oxide to silica ratio between about 0.3 and 0.6, 4 to 12% ofwater-soluble alkali metal sulfate and up to 15 water, moving andcirculating a mass of said particulate detergent, adding 2 to 30% waterto the moving and circulating particulate detergent to raise themoisture content thereof to 17 to 30% whereby the moisture issubstantially uniformly distributed throughout the mass of saidparticles and lightly compacting the resulting particles at a pressureof 3-100 p.s.i. into form retaining tablets which are readilydisintegrable in water, soluble therein and resistant to breakage whensubjected to shipping shocks.

4. A process for manufacturing a detergent tablet which comprises makingan aqueous mixture of a detergent composition comprising 6 to 14% of anonyl phenol polyoxyethylene ethanol in which the polyoxyethyleneethanol is of 9 to 10 oxyethylene units, to 40% sodium tripolyphosphate,20 to 40% sodium silicate of Na O:SiO ratio of about 0.4, 4 to 12% ofsodium sulfate and 8 to 12% water, spray drying the aqueous mixture in aheated drying gas to a particulate detergent of such composition, movingand circulating a mass of said particulate detergent, adding 7 to 17%water to the moving and circulating particulate detergent to raise themoisture content thereof to 19 to 25% whereby the moisture issubstantially uniformly distributed throughout the mass of saidparticles and lightly compacting the resulting particles at a pressureof 3 to 25 p.s.i. into form retaining tablets of a bulk density betweenabout 0.3 and 0.5 grams per cubic centimeter, said tablets being readilydisintegrable in water, soluble therein and resistant to breakage whensubjected to shipping shocks.

5. A process for manufacturing a detergent tablet which comprises makingan aqueous mixture of a detergent composition comprising about 10% ofnonyl phenol polyoxyethylene ethanol in which the polyoxyethyleneethanol averages about 9.5 oxyethylene units per molecule, about sodiumtripolyphosphate, about 30% of sodium silicate of Na O:SiO ratio ofabout 1:2.35, about 7% of sodium sulfate and about 10% water, allpercentages being on a final product basis except that for water, mixingthe aqueous composition to distribute the various constituents thereofevenly, spraying the homogeneous mixture under pressure in fine dropletform into a drying gas and drying said droplets to particlessubstantially between 8 and 100 mesh and of bulk density of about 0.2 to0.6 gram per cubic centimeter, moving and circulating a mass of saidparticulate detergent, adding about 12% water to the moving andcirculating particulate detergent to raise the moisture content thereofto about 22% whereby the moisture is substantially uniformly distributedthroughout the mass of said particles and lightly compacting theresulting particles at a pressure of 3-25 p.s.i. into form retainingtabletswhich are readily disintegrable in wash water, soluble thereinand resistant to breakage when subjected to shipping shocks.

6. A detergent tablet which comprises 2 to 20% of a water-solublesynthetic organic detergent selected from the group consisting ofsulfated and sulfonated anionic detergents and nonionic detergentscontaining hydrophilic and hydrophobic portions in the molecule of whichat least the hydrophilic portion includes a plurality of lower joinedalkylene oxide groups or mixtures thereof, 25 to 40% of a water solublealkali metal polyphosphate, 20 to 50% of a water soluble alkali metalsilicate, 3.5 to 10% of water soluble alkali metal sulfate and 17 to 30%water, the tablet being in the form of particles compacted at a pressureof 3-100 p.s.i., which tablet is disintegrable in wash water, solubletherein, form retaining and resistant to breakage when subjected toshipping shocks.

7. A detergent tablet which comprises 6 to 14% of a nonionic syntheticorganic detergent which is a higher alkyl phenol poly lower alkoxyalkanol, 25 to 40% of a water soluble alkali metal tripolyphosphate, 20to 40% of a water soluble alkali metal silicate of metal oxide to silicaratio between about 0.3 and 0.6, 3.5 to 10% of water soluble alkalimetal sulfate and 17 to 30% water, the tablet being in the form ofparticles compacted at a pressure of 3-100 p.s.i., which tablet is of abulk density between about 0.3 to 0.5 gram per cubic centimeter, formretaining and resistant to breakage when subjected to shipping shocksand also floats in wash water, disintegrates rapidly therein and issubstantially completely soluble therein.

8. A detergent tablet which comprises 6 to 14% of a nonyl phenolpolyoxyethylene ethanol in which the polyoxyethylene ethanol is of 9 to10 oxyethylene units, 25 to 40% sodium tripolyphosphate, 20 to 40%sodium silicate of Na O:SiO ratio of about 0.4, 3.5 to 10% of sodiumsulfate and 10 to 25% water, the tablet being in the form of spray driedparticles compacted at a pressure of 3-100 p.s.i., which tablet is of abulk density between about 0.3 and 0.5 gram per cubic centimeter, formretaining and resistant to breakage when subjected to shipping shocksand also floats in wash water, disintegrates rapidly therein and issubstantially completely soluble therein.

9. A detergent tablet which comprises about 10% of nonyl phenolpolyoxyethylene ethanol in which the polyoxyethylene ethanol averagesabout 9.5 oxyethylene units per molecule, about 30% of sodiumtripolyphosphate, about 30% of sodium silicate of Na O:Si0 ratio ofabout 1:2.35, about 7% of sodium sulfate and about 22% Water, the tabletbeing in the form of spray dried particles compacted at a pressure of3-100 p.s.i., which tablet is of a bulk density between about 0.3 and0.5 gram per cubic centimeter, form retaining and resistant to breakagewhen subjected to shipping shocks and also floats in wash water,disintegrates rapidly therein and is substantially completely solubletherein.

References Cited by the Examiner UNITED STATES PATENTS 2,875,155 2/ 1959Miles 252--138 3,081,267 3/1963 Laskey 252- FOREIGN PATENTS 510,5553/1955 Canada.

JULIUS GREENWALD, Primary Examiner.

ALBERT T. MEYERS, Examiner.

1. A PROCESS FOR MANUFACTURING A DETERGENT TABLET WHICH COMPRISESPRODUCING A PARTICULATE DETERGENT COMPOSITION COMPRISING 2 TO 20% OF AWATER-SOLUBLE SYNTHETIC ORGANIC DETERGENT SELECTED FROM THE GROUPCONSISTING OF SULFATED AND SULFONATED ANIONIC DETERGENTS ANDWATER-SOLUBLE NONIONIC DETERGENTS CONTAINING BOTH HYDROPHILIC ANDHYDROPHOBIC PORTIONS IN THE MOLECULE IN WHICH AT LEAST THE HYDROPHILICPORTION INCLUDES A PLURALITY OF LOWER JOINED ALKYLENE OXIDE GROUPS ORMIXTURES THEREOF, 25 TO 40% OF A WATER-SOLUBLE ALKALI METALPOLYPHOSPHATE, 20 TO 50% OF A WATER-SOLUBLE ALKALI METAL SILICATE, 4 TO12% OF A WATER-SOLUBLE ALKALI METAL SULFATE AND UP TO ABOUT 15% WATER,MOVING AND CIRCULATING A MASS OF SAID PARTICULATE DETERGENT, ADDING 2 TO30% WATER TO THE MOVING AND CIRCULATING PARTICULATE DETERGENT TO RAISETHE MOISTURE CONTENT THEREOF TO 17 TO 30% WHEREBY THE MOISTURE ISSUBSTANTIALLY UNIFORMLY DISTRIBUTED THROUGHOUT THE MASS OF SAIDPARTICLES AND LIGHTLY COMPACTING THE RESULTING PARTICLES AT A PRESSUREOF 3-100 P.S.I. INTO FORM RETAINING TABLETS WHICH ARE READILYDISINTEGRABLE IN WASH WATER, SOLUBLE THEREIN AND RESISTANT TO BREAKAGEWHEN SUBJECTED TO SHIPPING SHOCKS.